Method 1 – Using date

The following example will calculate the execution time in seconds by subtracting the system date and time in seconds since 1970-01-01 00:00:00 UTC once right before the script goes to the computation part and once right after.

In order to get the system date and time in seconds since 1970-01-01 00:00:00 UTC we use the command date +%s.

#!/bin/bash
#Print the system date and time in seconds since 1970-01-01 00:00:00 UTC
startTime=$(date +%s);
#We pick a random number between 1 and 10.
#Then we delay the execution for that amount of seconds.
sleep $(( (RANDOM % 10) + 1 ));
endTime=$(date +%s);
#Subtract endTime from startTime to get the total execution time
totalTime=$(($endTime-$startTime));
echo "Process finished after $totalTime seconds";
exit 0;

Method 2 – Using bash internal SECONDS variable

The following example will calculate the execution time in seconds by reseting the bash internal variable SECONDS to 0, forcing the shell to continue counting from there.

#!/bin/bash
#This variable expands to the number of seconds since the shell was started.
#We set it to 0, forcing the shell to continue counting from there.
SECONDS=0;
#We pick a random number between 1 and 10.
#Then we delay the execution for that amount of seconds.
sleep $(( (RANDOM % 10) + 1 ));
echo "Process finished after $SECONDS seconds";
exit 0;

Method 3 – Using bash time

The following example uses the bash time command, which reports the time consumed by a pipeline’s execution.
When time command is executed without its complete path, then the bash built-in time command is executed, instead of the GNU time command. We will use the bash time command in this example and we will use it to run a whole block of commands.
Please note that time command will return the time in seconds as a float (i.e. there will be decimal places. e.g. 1 will be printed as 1.00).

#!/bin/bash
#The bash time command reports the time consumed by pipeline's execution
#When time command is executed without its complete path, then the bash built-in time command is executed, instead of the GNU time command.
#We will use the bash time command in this example and we will use it to run a whole block of commands.
#We change the output format of time to print elapsed real time in seconds.
TIMEFORMAT="%E";
#We pick a random number between 1 and 10.
#Then we delay the execution for that amount of seconds.
totalTime=`time ( sleep $(( (RANDOM % 10) + 1 )) ) 2>&1`;
#Please note that time command will return the time in seconds as a float (i.e. there will be decimal places. e.g. 1 will be printed as 1.00).
#This will happen as time has build-in more precision than the first two methods presented here.
echo "Process finished after $totalTime seconds";
totalTimeBlock=`time (
sleep $(( (RANDOM % 10) + 1 ));
sleep $(( (RANDOM % 10) + 1 ));
) 2>&1`;
echo "Block finished after $totalTimeBlock seconds";
exit 0;

Method 4 – Using GNU time

The GNU time command runs the specified program command with the given arguments.
When time command is executed without its complete path (in our case it was /usr/bin/time), then the bash built-in time command is executed, instead of the GNU time command. To make sure we use the GNU time command, we use which to get the full path of the time command.
Please note that time command will return the time in seconds as a float (i.e. there will be decimal places. e.g. 1 will be printed as 1.00).

#!/bin/bash
#The time command runs the specified program command with the given arguments.
#When time command is executed without its complete path (in our case it was /usr/bin/time), then the bash built-in time command is executed, instead of the GNU time command.
#To make sure we use the GNU time command, we use which to get the full path of the time command.
time=`which time`;
#We pick a random number between 1 and 10.
#Then we delay the execution for that amount of seconds.
#We change the output format of time to print elapsed real time in seconds.
totalTime="$( $time -f '%e' sleep $(( (RANDOM % 10) + 1 )) 2>&1 1>/dev/null )";
#Please note that time command will return the time in seconds as a float (i.e. there will be decimal places. e.g. 1 will be printed as 1.00).
#This will happen as time has build-in more precision than the first two methods presented here.
echo "Process finished after $totalTime seconds";
exit 0;

Notes

RANDOM internal variable

Each time RANDOM internal variable is referenced, a random integer between 0 and 32767 is generated.

By using the RANDOM variable in this command $(( (RANDOM % 10) + 1 )); we perform a modulo on the random value with the static value 10. This way we force the range of valid values to be between 0 and 9.
Later, we add 1 to that value to shift the range to be between 1 and 10.

The following code can be used to convert some time in seconds to minutes, hours and days in bash.
It will print on screen the converted values only if they are not 0. i.e If the resulting days is 0, it will not print the text for days at all.
You can use it in any script without copy pasting everything in it by executing the following command source ./convertAndPrintSeconds.sh.
Doing so, it will load to your script the function that is defined in convertAndPrintSeconds.sh, making it available for you to use (something like including code in C, with some caveats).

The following script can be used to print colored text in bash.
You can use it in any script without copy pasting everything in it by executing the following command source cecho.sh.
Doing so, it will load to your script the functions that are defined in cecho.sh, making them available for you to use (something like including code in C, with some caveats).

Usage

Function cecho accepts the options to set the color and to control if a new line should be print.
Parameter -c or --color define the color for the print. See the array colors for the available options.
Parameter -n or --noline directs the system not to print a new line after the content.
The last parameter is the string message to be printed.
Functions warning, error and information are using cecho to print in color.
These three functions always print a new line and they have hardcoded one color set for each.

Example

#Get the name of the script currently being executed
scriptName=$(basename $(test -L "$0" && readlink "$0" || echo "$0"));
#Get the directory where the script currently being executed resides
scriptDirDIR=$(cd $(dirname "$0") && pwd);
#Print in blue color with no new line
cecho -n -c 'blue' "$scriptDir";
#Print in red color with a new line following the message
cecho -c 'red' "$scriptName";
#Using the information() function to print in blue followed by a new line
information ‘End of script’;

In the results you need to find the line Hosted network supported and verify that the value is set to Yes, if it is not, then you cannot proceed with this wireless network adapter.

In case you got a permission error on the above command, try to open a new Command Prompt with admin rights.

Press the keys Windows+X, in the pop-up menu select Command Prompt (Admin). If your account has enough access rights, a new run command prompt will appear. In the new Command Prompt (Admin) type NETSH WLAN show drivers, the results should be similar to above.

If this failed as well, you cannot proceed with the current account, you either need to sign in with another account or ask your system administrator to perform this task for you.

How to setup the hotspot

Update ssid=BYTEFREAKS with the name that you want to give your network. e.g. ssid=MY_NETWORK.

Update key=0123456789 with the password that you want to give your network. e.g. ssid=y0m2ZSQ3ng.

The new network will use WPA/WPA2 PSK security policy so your password needs to be at least 8 characters long.

The results will be similar to the following block.

C:\Users\bytefreaks>NETSH WLAN set hostednetwork mode=allow ssid=HIDDEN007 key=0123456789
The hosted network mode has been set to allow.
The SSID of the hosted network has been successfully changed.
The user key passphrase of the hosted network has been successfully changed.

How to activate the hotspot

Once the Hosted Network is created, enter the following command as is to activate it

How to share internet connection with the hotspot

Press on the keyboard Windows+X to open the Power User menu, and select Network Connections.

You will notice that a there is a new device in this list. The name of this device will be something line Local Area Connection* 12. That device is the new virtual device you created in the previous step to create the hotspot.

Right-click the other network adapter, that has an active internet connection and select Properties.

Click on the Sharing tab.

Enable the Allow other network users to connect through this computer's Internet connection option.

From the Home networking connection drop-down menu select the virtual device that we created.

Click OK to close the configuration and apply the changes.

By completing this step, all devices connected to your Hotspot will have access to the internet via the connection of the second network device.

Once we got the OS started, we executed yum update -y to update all installed packages that were older than the versions in the repositories.
After the update process was complete, we then tried to install terminator using yum.

Recently we had to download texinfo from version 5.1 to any version less than version 5 series.
We used texinfo version 4.13 which is the latest in the version 4 series.

We were trying to compile some tools using an older version of gcc. Instead of using 4.8.5, we used 4.8.2 to achieve our goal and that caused a problem with some .texi files.

Methodology

#Making sure we are not missing any 32bit libraries since we are on a 64bit machine
yum install glibc.i686 ncurses-libs.i686;
#Download the source code
wget http://ftp.gnu.org/gnu/texinfo/texinfo-4.13.tar.gz;
#Extract the files
tar -zxf texinfo-4.13.tar.gz;
#Navigate to the folder
cd texinfo-4.13;
#Configure the installation and make all necessary checks
./configure;
#Build
make;
#Install
sudo make install;

We were trying to compile some tools and they required using that older version of gcc.
To compile the old version of the gcc we used the version version that was shipped with the distribution.

Methodology

#Making sure we are not missing any 32bit libraries since we are on a 64bit machine
yum install glibc.i686 ncurses-libs.i686;
#Download the source code
wget http://ftp.gnu.org/gnu/gcc/gcc-4.8.2/gcc-4.8.2.tar.gz;
#Extract the files
tar -xvf gcc-4.8.2.tar.gz;
#Navigate to the folder
cd gcc-4.8.2/;
#Make sure we have all dependencies met
./contrib/download_prerequisites;
#Configure the installation and assign the installation folder to be /usr/local/gcc/4.8.2. Finally make all necessary checks before compilation.
./configure --prefix=/usr/local/gcc/4.8.2;
#Build
make;
#Install
sudo make install;

Assuming you have the following scenario: you are connected to a remote Windows machine via remote desktop and you need to restart it.
Soon you will realize that there is no restart button on the Start menu to click on….
So.. without that button, how do you restart your machine???

Do not fret as there is a way!

To Restart the remote Windows machine

Press the keys Windows+R on the keyboard together, it will pop-up the run command screen.
In the input line type shutdown /r /t 0 and hit the Enter button to restart the machine immediately.

The /r option instructs the machine to reboot

The /t 0 option sets the number of seconds to delay before executing the restart to 0 (initiate restart process immediately)

To Shut Down the remote Windows machine

Press the keys Windows+R on the keyboard together, it will pop-up the run command screen.
In the input line type shutdown /s and hit the Enter button to restart the machine immediately.

To Stop a Shut Down or Restart process

To try and stop a shut down process, type shutdown /a and hit enter, it will attempt to abort the shutdown/restart sequence.
Keep in mind though that there still is a high chance for this to fail.

We needed this tool to configure the Gnome 3 native network client to connect to a specific Cisco VPN network.
During the configuration we setup a “Cisco Compatible VPN (vpnc)” VPN.

* Please note that this tool is NOT a hacking nor cracking tool. In order for you to make any use of it, you need to have a valid PCF file given to you by your system administrator. It is only useful when you need to get the group password to configure a system that does not accept the PCF file with the encrypted password.

To compile the code you can use one of the following two methods:

Compilation method 1

If the package libgcrypt-devel is not installed you will get a prompt message as follows, which will instruct you to install the missing package.
You need to type y to both questions so that the installation will proceed. Once the installation is done, execute once more the compilation command.

As you can see below, you might get a whole bunch of errors, ignore them and try to compile once more. It seems to be a bug that will not affect the end result (at least in this scenario).

gcc -Wall -o cisco-decrypt cisco-decrypt.c $(libgcrypt-config --libs --cflags)
bash: libgcrypt-config: command not found...
Install package 'libgcrypt-devel' to provide command 'libgcrypt-config'? [N/y] y
Proceed with changes? [N/y] y
gcc: error: Waiting: No such file or directory
gcc: error: in: No such file or directory
gcc: error: queue...: No such file or directory
gcc: error: Loading: No such file or directory
gcc: error: list: No such file or directory
gcc: error: of: No such file or directory
gcc: error: packages....: No such file or directory
gcc: error: The: No such file or directory
gcc: error: following: No such file or directory
gcc: error: packages: No such file or directory
gcc: error: have: No such file or directory
gcc: error: to: No such file or directory
gcc: error: be: No such file or directory
gcc: error: installed:: No such file or directory
gcc: error: libgcrypt-devel-1.6.6-1.fc24.x86_64: No such file or directory
gcc: error: Development: No such file or directory
gcc: error: files: No such file or directory
gcc: error: for: No such file or directory
gcc: error: the: No such file or directory
gcc: error: libgcrypt: No such file or directory
gcc: error: package: No such file or directory
gcc: error: libgpg-error-devel-1.24-1.fc24.x86_64: No such file or directory
gcc: error: Development: No such file or directory
gcc: error: files: No such file or directory
gcc: error: for: No such file or directory
gcc: error: the: No such file or directory
gcc: error: libgpg-error: No such file or directory
gcc: error: package: No such file or directory
gcc: error: Waiting: No such file or directory
gcc: error: in: No such file or directory
gcc: error: queue...: No such file or directory
gcc: error: Waiting: No such file or directory
gcc: error: for: No such file or directory
gcc: error: authentication...: No such file or directory
gcc: error: Waiting: No such file or directory
gcc: error: in: No such file or directory
gcc: error: queue...: No such file or directory
gcc: error: Downloading: No such file or directory
gcc: error: packages...: No such file or directory
gcc: error: Requesting: No such file or directory
gcc: error: data...: No such file or directory
gcc: error: Testing: No such file or directory
gcc: error: changes...: No such file or directory
gcc: error: Installing: No such file or directory
gcc: error: packages...: No such file or directory

Compilation method 2

In case the above method does not work for you for some reason, you can try the following.

gcc -Wall -o cisco-decrypt cisco-decrypt.c -lgcrypt

If the package libgcrypt-devel is not installed you will get an error as follows.

Inside there was a USB with a couple of manuals and an installation package named Open_AT_Application_Framework_v2-51_Full_Installer.zip.
We installed the software, which included the USB drivers and an IDE based on eclipse named Developer Studio.
The version of Developer Studio was 2.3.2 and we installed it on Windows 10.
After the installation was complete, we did a check for updated as well.

When we tried to connect to the device from the Target Management perspective, we could not connect to the COM1 port on the computer as it was not visible at all in the Devices List.

Later, we found that there were newer versions of the tool online (version 3 and version 4). So we downloaded the version 3 from this link that we found on this page on the line